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From:Sergey Petrunya Date:September 9 2009 7:40pm
Subject:Contribution: Fix for BUG#42742
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Hi,

I'd like to offer the following bugfix under BSD licence:

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== The patch  ==

At file:///home/psergey/dev/mysql-next-fix-subq/
------------------------------------------------------------
revno: 2817
revision-id: psergey@stripped
parent: psergey@stripped
committer: Sergey Petrunya <psergey@stripped>
branch nick: mysql-next-fix-subq
timestamp: Mon 2009-07-06 18:33:29 +0400
message:
  BUG#42742: crash in setup_sj_materialization, Copy_field::set
  - If a semi-join strategy covers certain [first_table; last_table] 
    range in join order, do reset the sj_strategy member for all tables
    within the range, except the first one.
    Failure to do so caused EXPLAIN/execution code to try applying two 
    strategies at once which would cause all kinds of undesired effects. 
=== modified file 'mysql-test/r/subselect_sj2.result'
--- a/mysql-test/r/subselect_sj2.result	2009-03-21 15:31:38 +0000
+++ b/mysql-test/r/subselect_sj2.result	2009-07-06 14:33:29 +0000
@@ -689,3 +689,19 @@
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const
tables
 drop table t1, t2;
+# 
+# BUG#42742: crash in setup_sj_materialization, Copy_field::set
+# 
+create table t3 ( c1 year) engine=innodb;
+insert into t3 values (2135),(2142);
+create table t2 (c1 tinytext,c2 text,c6 timestamp) engine=innodb;
+# The following must not crash, EXPLAIN should show one SJ strategy, not a mix:
+explain select 1 from t2 where 
+c2 in (select 1 from t3, t2) and
+c1 in (select convert(c6,char(1)) from t2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	1	Using where
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	1	
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	1	Using where; Using join buffer
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	FirstMatch(t2); Using join buffer
+drop table t2, t3;

=== modified file 'mysql-test/r/subselect_sj2_jcl6.result'
--- a/mysql-test/r/subselect_sj2_jcl6.result	2009-06-19 09:12:06 +0000
+++ b/mysql-test/r/subselect_sj2_jcl6.result	2009-07-06 14:33:29 +0000
@@ -693,6 +693,22 @@
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const
tables
 drop table t1, t2;
+# 
+# BUG#42742: crash in setup_sj_materialization, Copy_field::set
+# 
+create table t3 ( c1 year) engine=innodb;
+insert into t3 values (2135),(2142);
+create table t2 (c1 tinytext,c2 text,c6 timestamp) engine=innodb;
+# The following must not crash, EXPLAIN should show one SJ strategy, not a mix:
+explain select 1 from t2 where 
+c2 in (select 1 from t3, t2) and
+c1 in (select convert(c6,char(1)) from t2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	1	Using where
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	1	Using join buffer
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	1	Using where; Using join buffer
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	FirstMatch(t2); Using join buffer
+drop table t2, t3;
 set join_cache_level=default;
 show variables like 'join_cache_level';
 Variable_name	Value

=== modified file 'mysql-test/t/subselect_sj2.test'
--- a/mysql-test/t/subselect_sj2.test	2009-03-21 15:31:38 +0000
+++ b/mysql-test/t/subselect_sj2.test	2009-07-06 14:33:29 +0000
@@ -872,3 +872,15 @@
 explain select 1 from t2 where c2 = any (select log10(null) from t1 where c6 <null)  ;
 drop table t1, t2;
 
+--echo # 
+--echo # BUG#42742: crash in setup_sj_materialization, Copy_field::set
+--echo # 
+create table t3 ( c1 year) engine=innodb;
+insert into t3 values (2135),(2142);
+create table t2 (c1 tinytext,c2 text,c6 timestamp) engine=innodb;
+-- echo # The following must not crash, EXPLAIN should show one SJ strategy, not a mix:
+explain select 1 from t2 where 
+  c2 in (select 1 from t3, t2) and
+  c1 in (select convert(c6,char(1)) from t2);
+drop table t2, t3;
+

=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc	2009-07-06 07:57:39 +0000
+++ b/sql/sql_select.cc	2009-07-06 14:33:29 +0000
@@ -7916,7 +7916,11 @@
     
     uint i_end= first + join->best_positions[first].n_sj_tables;
     for (uint i= first; i < i_end; i++)
+    {
+      if (i != first)
+        join->best_positions[i].sj_strategy= SJ_OPT_NONE;
       handled_tabs |= join->best_positions[i].table->table->map;
+    }
 
     if (tablenr != first)
       pos->sj_strategy= SJ_OPT_NONE;

BR
 Sergey
-- 
Sergey Petrunia, Software Developer
Monty Program AB, http://askmonty.org
Blog: http://s.petrunia.net/blog
Thread
Contribution: Fix for BUG#42742Sergey Petrunya9 Sep
  • Re: Contribution: Fix for BUG#42742Jay Pipes9 Sep
  • Re: Contribution: Fix for BUG#42742Masood Mortazavi16 Sep
    • Re: Contribution: Fix for BUG#42742Vladimir Shebordaev16 Sep
      • Re: Contribution: Fix for BUG#42742Giuseppe Maxia16 Sep
    • Re: Contribution: Fix for BUG#42742Kristian Nielsen16 Sep
      • Re: Contribution: Fix for BUG#42742Giuseppe Maxia16 Sep
        • Re: Contribution: Fix for BUG#42742Masood Mortazavi17 Sep